/*
 * server-coap.c -- RIOT example
 *
 * Copyright (C) 2023 Jon Shallow <supjps-libcoap@jpshallow.com>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * This file is part of the CoAP library libcoap. Please see README for terms
 * of use.
 */

#include "coap_config.h"
#include <coap3/coap.h>
#include "server-coap.h"
#include "macros/utils.h"

#ifdef CONFIG_LIBCOAP_USE_PSK
#define COAP_USE_PSK CONFIG_LIBCOAP_USE_PSK
#else /* CONFIG_LIBCOAP_USE_PSK */
#define COAP_USE_PSK NULL
#endif /* CONFIG_LIBCOAP_USE_PSK */

static volatile int running = 0;
static int quit;

coap_context_t *main_coap_context;

static coap_time_t clock_offset;
/* changeable clock base (see handle_put_time()) */
static coap_time_t my_clock_base = 0;
static coap_resource_t *time_resource = NULL; /* just for testing */

static void
hnd_get_time(coap_resource_t *resource, coap_session_t  *session,
             const coap_pdu_t *request, const coap_string_t *query,
             coap_pdu_t *response) {
  unsigned char buf[40];
  size_t len;
  coap_tick_t now;
  coap_tick_t t;

  (void)resource;
  (void)session;
  (void)request;
  /* FIXME: return time, e.g. in human-readable by default and ticks
   * when query ?ticks is given. */

  /* if my_clock_base was deleted, we pretend to have no such resource */
  coap_pdu_set_code(response, my_clock_base ? COAP_RESPONSE_CODE_CONTENT :
                    COAP_RESPONSE_CODE_NOT_FOUND);
  if (my_clock_base) {
    coap_add_option(response, COAP_OPTION_CONTENT_FORMAT,
                    coap_encode_var_safe(buf, sizeof(buf),
                                         COAP_MEDIATYPE_TEXT_PLAIN),
                    buf);
  }

  coap_add_option(response, COAP_OPTION_MAXAGE,
                  coap_encode_var_safe(buf, sizeof(buf), 0x01), buf);

  if (my_clock_base) {

    /* calculate current time */
    coap_ticks(&t);
    now = my_clock_base + (t / COAP_TICKS_PER_SECOND);

    if (query != NULL
        && coap_string_equal(query, coap_make_str_const("ticks"))) {
      /* output ticks */
      len = snprintf((char *)buf, sizeof(buf), "%u", (unsigned int)now);
      coap_add_data(response, len, buf);
    }
  }
}

static void
init_coap_resources(coap_context_t *ctx) {
  coap_resource_t *r;
#if 0
  r = coap_resource_init(NULL, 0, 0);
  coap_register_handler(r, COAP_REQUEST_GET, hnd_get_index);

  coap_add_attr(r, coap_make_str_const("ct"), coap_make_str_const("0"), 0);
  coap_add_attr(r, coap_make_str_const("title"), coap_make_str_const("\"General Info\""), 0);
  coap_add_resource(ctx, r);
#endif
  /* store clock base to use in /time */
  my_clock_base = clock_offset;

  r = coap_resource_init(coap_make_str_const("time"), 0);
  if (!r) {
    goto error;
  }

  coap_resource_set_get_observable(r, 1);
  time_resource = r;
  coap_register_handler(r, COAP_REQUEST_GET, hnd_get_time);
#if 0
  coap_register_handler(r, COAP_REQUEST_PUT, hnd_put_time);
  coap_register_handler(r, COAP_REQUEST_DELETE, hnd_delete_time);
#endif
  coap_add_attr(r, coap_make_str_const("ct"), coap_make_str_const("0"), 0);
  /* coap_add_attr(r, coap_make_str_const("title"),
                   coap_make_str_const("\"Internal Clock\""), 0); */
  coap_add_attr(r, coap_make_str_const("rt"), coap_make_str_const("\"ticks\""), 0);
  coap_add_attr(r, coap_make_str_const("if"), coap_make_str_const("\"clock\""), 0);

  coap_add_resource(ctx, r);
#if 0
  if (coap_async_is_supported()) {
    r = coap_resource_init(coap_make_str_const("async"), 0);
    coap_register_handler(r, COAP_REQUEST_GET, hnd_get_async);

    coap_add_attr(r, coap_make_str_const("ct"), coap_make_str_const("0"), 0);
    coap_add_resource(ctx, r);
  }
#endif

  return;
error:
  coap_log_crit("cannot create resource\n");
}

static int
init_coap_context_endpoints(const char *use_psk) {
  coap_address_t listenaddress;
  gnrc_netif_t *netif = gnrc_netif_iter(NULL);
  ipv6_addr_t addr;
  char addr_str[INET6_ADDRSTRLEN + 8];
  int scheme_hint_bits = 1 << COAP_URI_SCHEME_COAP;
  coap_addr_info_t *info = NULL;
  coap_addr_info_t *info_list = NULL;
  coap_str_const_t local;
  int have_ep = 0;

  /* Get the first address on the interface */
  if (gnrc_netif_ipv6_addrs_get(netif, &addr, sizeof(addr)) < 0) {
    puts("Unable to get first address of the interface");
    return 0;
  }

  coap_address_init(&listenaddress);
  listenaddress.addr.sin6.sin6_family = AF_INET6;
  memcpy(&listenaddress.addr.sin6.sin6_addr, &addr,
         sizeof(listenaddress.addr.sin6.sin6_addr));
  coap_print_ip_addr(&listenaddress, addr_str, sizeof(addr_str));
  coap_log_info("Server IP [%s]\n", addr_str);

  main_coap_context = coap_new_context(NULL);
  if (!main_coap_context) {
    return 0;
  }

  if (use_psk && coap_dtls_is_supported()) {
    coap_dtls_spsk_t setup_data;

    /* Need PSK set up before setting up endpoints */
    memset(&setup_data, 0, sizeof(setup_data));
    setup_data.version = COAP_DTLS_SPSK_SETUP_VERSION;
    setup_data.psk_info.key.s = (const uint8_t *)use_psk;
    setup_data.psk_info.key.length = strlen(use_psk);
    coap_context_set_psk2(main_coap_context, &setup_data);
    scheme_hint_bits |= 1 << COAP_URI_SCHEME_COAPS;
  }

  local.s = (uint8_t *)addr_str;
  local.length = strlen(addr_str);
  info_list = coap_resolve_address_info(&local, COAP_DEFAULT_PORT,
                                        COAPS_DEFAULT_PORT,
                                        0, 0,
                                        0,
                                        scheme_hint_bits,
                                        COAP_RESOLVE_TYPE_REMOTE);
  for (info = info_list; info != NULL; info = info->next) {
    coap_endpoint_t *ep;

    ep = coap_new_endpoint(main_coap_context, &info->addr, info->proto);
    if (!ep) {
      coap_log_warn("cannot create endpoint for proto %u\n",
                    info->proto);
    } else {
      have_ep = 1;
    }
  }
  coap_free_address_info(info_list);
  if (!have_ep) {
    return 0;
  }

  return 1;
}

void *
server_coap_run(void *arg) {
  (void)arg;

  /* Initialize libcoap library */
  coap_startup();

  coap_set_log_level(COAP_MAX_LOGGING_LEVEL);

  if (!init_coap_context_endpoints(COAP_USE_PSK)) {
    goto fail;
  }

  /* Limit the number of idle sessions to save RAM */
  coap_context_set_max_idle_sessions(main_coap_context, 2);
  clock_offset = 1; /* Need a non-zero value */
  init_coap_resources(main_coap_context);

  coap_log_info("libcoap server ready\n");
  /* Keep on processing ... */
  while (quit == 0) {
    coap_io_process(main_coap_context, 1000);
  }
fail:
  /* Clean up library usage so client can be run again */
  coap_free_context(main_coap_context);
  main_coap_context = NULL;
  coap_cleanup();
  running = 0;
  quit = 0;
  coap_log_info("libcoap server stopped\n");
  return NULL;
}

static char server_stack[THREAD_STACKSIZE_MAIN +
                                               THREAD_EXTRA_STACKSIZE_PRINTF];

static
void
start_server(void) {
  kernel_pid_t server_pid;

  /* Only one instance of the server */
  if (running) {
    puts("Error: server already running");
    return;
  }

  /* The server is initialized */
  server_pid = thread_create(server_stack,
                             sizeof(server_stack),
                             THREAD_PRIORITY_MAIN - 1,
                             THREAD_CREATE_STACKTEST,
                             server_coap_run, NULL, "libcoap_server");

  /* Uncommon but better be sure */
  if (server_pid == EINVAL) {
    puts("ERROR: Thread invalid");
    return;
  }

  if (server_pid == EOVERFLOW) {
    puts("ERROR: Thread overflow!");
    return;
  }

  running = 1;
  return;
}

static
void
stop_server(void) {
  /* check if server is running at all */
  if (running == 0) {
    puts("Error: libcoap server is not running");
    return;
  }

  quit = 1;

  puts("Stopping server...");
}

void
server_coap_init(int argc, char **argv) {
  if (argc < 2) {
    printf("usage: %s start|stop\n", argv[0]);
    return;
  }
  if (strcmp(argv[1], "start") == 0) {
    start_server();
  } else if (strcmp(argv[1], "stop") == 0) {
    stop_server();
  } else {
    printf("Error: invalid command. Usage: %s start|stop\n", argv[0]);
  }
  return;
}
